Speed-indicator.



G. W. BLACKBURN.,

SPEED INDICATOR.

APPLICATION mm 1AN.21.19{5.

l Patente Nov. 13, i917.'

fave/ if @Maw/@am PATENT OFFICE GUY W. BLACKBURN or ELGIN, rLLIiyrOIs-f` srnnnLiNDIcATon.

To all wv/wm t may concern.' 1 A Be it known that I, Gruirl WT. BLACKBURN,

a citizen of the United States, residingl aty Vwhich the following is a specification.V

`My invention relates to improvements in speed indicators, and has for one object to provide a new and improved form ofv speed indicator of lthe tachometer type for indicating the yspeed Vvof all kindslofv moving members. It is particularly"designed for use in connection with a speedometer for automobiles and the like, although itis of course obvious that other uses may be equally important. My invention-.is illustrated more or less diagrammatically in the accompanying drawings, wherein Figure l is a front elevation ofthespeedometer. i -V Fig. 2 is a sectionfthrough the speedometer case on an enlarged scale, showing the working parts in elevation. f .f

Fig. 3 is a section through t-he speedometer case on the same scale, showing parts in sideelevation. v i

Fig; 4: is a sectionalong thelinefl-etof Fig. y3. f

Fig; 5 is a detail side elevation inf `part section along the line 5 5 ofFig.` 3.

Fig. 6 is a detail section along ytheline 6-6of Fig. 3. 1.

Like parts are indicated'by the sameletter in all the gures.

I have. for the sake 0f convenience and cleaijness, confined my showingV andA discussion'to 'the so-called speedometer or speed indicator head, namely `that part ofthe instrument which registers the result, and I haveomitted all reference tothe driving shaft, driving connections and the like, except so far as they are directly connected to and form a part of the speedometer head.

A is a rectangularliousing or box provided with lugs A1, in order to makeits attachni'ent to any suitable appointment ofy support. This box has a glass cover `A2, and

behind the glassy cover "a dial or indicator plate A3 slotted as at A4.' It will be understood that they housing normally assumes a vertical position, and thattlierefore the slot the working y rollers or wheels t,

Serial No. 3,589.

lSpeciicaticm of Letters Patent. `Pd-ftentdN`0`n 13,Y 191.7, y Application yinea January 21, 1915. I'

in the dial plate is a vertical one. This disk is dividedinto Ysuitable space intervals and lettered or indexed for miles perhour, revolutionslper minute, or any suitablequantity `which it is ydesired maybe readdirec't from the instrument. For the sake of ,convenience I haveillustrated it as an automobile speedometer, andv therefore the scaleis divided intomiles `.per hour. A5 is the usual typeof odometer contained in thehousing fof the speedometer for the purposeof coin-v puting the mileage covered,` or the total numberot revolutions or anything else as the case maybe'.- AG is a connection head provided for the ypurpose of connecting the speedometer in this case to the iexible shaft, which transmits the power from the moving part to the speedometer and Alisa stub 'end shaft slotted asV indicated in connection with such lflexible shaft. u

, B is a vertical mutilated screw. i Itis free ported and; guided at. itsrlower vend bythe 4stem- B3 mounted onthe stub end shaft A7.

and carrying a worm B* todrive a worm wheelB5 which in turn operates. theodometer. 1

C, C, are guide rodsor railsheld in the housing l-Lparallelwvith the axis of the screw B. C1 is acarriage having grooved m2, C2, C3, C3, engaging opposed sides of the trackbars C toflimit the carriage to movement along such bars parallel with the axis of thev shaft. This car- .riagecarries a linger C4 which projects out of the slot A, and terminates in a` pointer C5. C6 is a spring arm fastened at one end in fixed position on the carriage C. It carries atvits other endA rotatably mountedthe'reon a grooved roller C7. This-grooved roller and the relation between it and the slot is important, as will laterappear.

It will be noted that thespring tends t0 press the roller yieldingly against the screw B, and the roller is limited in its movement toward the ,screw by the set screw CS screwthreaded in the end of the spring, and having its end in opposition to the carriage C. The movement of the spring and roller in the opposite direction is limited by the `screw C9 screwfthreaded inthe carriage C1,

sharp thread with a comparatively greatv advance. Moreover, these threads have, as

Aindicated, a flat upper surface D, and an inclined end surface D1. It will be noted that the roller C7 is corrugated or grooved,

but not threaded. That is to say, the roller has a 'series of annular eorrugations about its periphery. Inmy preferred form there are five 'of them. Each one of them is lo- Vcated in a planeperpendicular to the aXis of the roller. Each one of them has a flat end surface D2, and an inclined upper sur- `face D3 of exactly the same dimensions as the screw threads on the screw B. The axis of the roller is inclined so that it is pervpendicular to the plane of the flat surface of each of the threads on the screw B at the point nearest to the roller. The result of this is that the live annular grooves on the roller engage each oneof the threads on the screw in smooth contact, and since the roller is spring pressed against the screw, it will be obvious that the carriage and roller can be pushed upward along the screw since the inclined surface on the thread and the inclined surface Aon the roller will slide one on the other to permit passage, but the roller cannot be moved down because the flat surface of the thread and tlielflat surface of the grooves are in engagement.

D4, D5 are notches formed in the side of the screw B, gradually increasing in width from the bottom upwardly so that `while the screw-threadV is almost continuous at the bottom, it is gradually shortened toward the top until at the extreme upper end a very appreciable portion of the screw thread yis cut away. These two notches are thus substantially V-shaped. In my preferred form one'side of the V is substantially parallel with the axis of the screw, and the other inclined thereto, Vthough under some circumstances it mightbe desirable to change this relation. Moreover, as indicated, one side of the V isinclined, and the other substair tially radial, as shown in Fig. l. i

It is obvious that, while I have preferred a particular number of threads, otherthread combinations might be used, and'that while I have used two slots, other'slot combinations mightbe used. My experience shows,

however, that best results rare obtained when such a number of slotsfand such a number of threads are used that the product .Of the two numbers is an uneven quantity. My experience further shows that it is desirable to have one anl even quantity, and the other an odd quantity, and I therefore show five threads and two slots, although it is perfectly obvious thatother combinations may ,produce the desired result.

It will be evident that while I have shown in my drawings an operative device, still many changes might be made in size, shape and arrangementlof parts without departing from the spirit of my invention.

The use and operation of my invention areas follows:-

Iith the parts at restthe carriage is at the bottom of its travel, and it points to zero. As the screw commences to rotate the carriage will. commence to rise, being di'awn up by the rotation of the screw in engagement with the roller. The i'ollei is `free to turn, and since it has five grooves in engagement with ve threads, the friction wear or load on any single groove or thread is a minimum. Thek carriage will thus rise until theA roller comes in contact with the slot, but it will then fall freely under the influence of gravity. If. at' this point the threaded cylinder `ceases its rotation, the roller will fall clear backv to zero, but-if it continues its'rotation, the Vroller will not have time to fall back to zero, and will be caught at some intermediate position and rise this time a little farther until it reaches the next slot. This will continue until the carriage being drawn up by theV roller, has climbed to such a height that when the roller `leaveszthe thread and comes to the slot,the carriage has time to fall'only just as far as it is carried up by the thread before the next slot'is reached. At that time the carriage will come substantially to rest, fluctuating, of course, slightly but not appreciably, indicating a certain speed. Thus a speed indication depends on the velocity of the thread cylinder and the width of the groove at any point. If high speeds are to vbe shown, a groove of rapidly increasing width is used; if a lower speed, a groove of less rapidly increasing width.

It is necessary to have a very line thread on the cylinder, because otherwise as the carriage moves up and down its fluctuations between contacts with the slot will be too great. If the slots are narrow, and if the threads are fine, very close accuracy may be obtained.

In other words, as the threaded cylinder rotates it propelstlie carriage upwardly until a. point is reached at which the carriage has just time to fall while out of contact with the thread `the' distance which it was raised while in contact with the` thread and attliat 4`point experience shows the carriage will rest until the speed changes at normal speeds in such Afluctiia'- Vthreads wound' side by side about f the spindle.

At thel point where the rolleris located, the threads on the spindleare inclined, the threads on the spindle have a distorted V; shaped contour, the threads 'on the roller have the same general contour only reversed ofthatof the roller threads to engage the spindle threads in Order that the roller lmay climb thescrew underfthe-inluence ofA the screw thread alone; The roller is' not' screw threaded but carries on its periphery, a series of annular threads, each'one arallol tofthe others, Vin ord'er that the 'lat surface on each of these threads may `engage the fiat surface on eachl of the spindle threads. This roller is-inclined'and its inclination to the spindle is Ajust enough to bring it into parallelism with aline perpendicular to the upper surfaceof `the spindlethread at the point of contact.

If the spindle were'merely threaded and not slotted the carrier would uponrotation of the spindle, movefrom bottom to top of the'spindleand then be able to move nov farther because there would then be a direct constant 'drive connection between they spindle and the indicator.- `In order lthatlthe posit-ion of the indicatorl may give/*a result which may be readfin speedreVOlutiOns, per minute, miles '-perhour, or'r the like, it is necessary that there be some variable connection or yrelation between the driving spindle andthe7 responding carrier; This variable relation enters in withthe lslot which makes the thread discontinuous and causes the carrier to lbe driven only through a portion of each revolution of fthevspindl'e.

During rthe remaining portion ythe carrier is freeto fall under r'the inluenceof grav'- ity." As the spindle 'turns the carrier is raised a Ycertain distance andy this raising continues until the end of the Vthread is spindle would drive-the carrier upfby a series of separate "implements, provided only therate of rotation of the spindle were great enough to catch the carrier before it completes-'its return under the infiuencel of gravity. 1

Ifrtheslot gradually increases in width upwardly the time available during each revolution for theI 'downward fall of the indicator will gradually increase as the indicator moves upwardly, and a point will ultimately be reached where afurther rise of the indicator will bring itin line' with such slot width that the indicator will fall blaclrjust as far as it came up. At thisl point it will stay oscillating possibly, but wavering at `the general level* wherein the time availablefor the return is just sufficient to enable the indicator to drop to the positionv fromwhich it started. If the speed rises, that point will be higher. yIt the speed drops that point will be lower;

Given the above relation between the indica'tor and `discontinuous thread,jit is perfectly easy to calibrate a yscale Awhich will 4 give a direct reading in speed, miles per hour or revolutions per minute as the case may be. If the speed range is lto be very great the difference -in width of slotfbetween top and bottom must be very great, the speed range to be small, then in variation with the width ofthe slotalso will be small. The slotis only important because it makes the thread discontinuous. It `might have one slot or a series of slots,- andthe downward drop of the indicatori'mayoccur once every revolution or a number oftimes every revolution. I prefer to have it occur twicey and to use a. quin-'tuple thread,

and I find that it is best to have either the tions between the parts so as at least to aconsiderable extent to prevent vibration and frustrating" of the' needle.

I claim: 7 L1A speed indicatorcomprising a rotatable mutilated screw, the eiective length of the screw thread progressively .decreasing upwardly,a carrier in contact with said screw, and means comprising said screw for raising said carrier.

2. A speed indicatorcomprising a screw, portions ofthe thread of said screw being cut away, said cut away portions increasing in width from the bottom of said screw upwardly,an`d 'a carrier free to, slide ina direction parallel with the aXis of said screw and in contact `with said screw.

3. A speed indicatorfcomprising a vertical screw havili thereon discontinuous threads, and V a carrier free to slidetherealongand provided with thready engaging means free to move only in a-'patli parallel v .with the axis of tliescrew, and a scale along which said carriei slides with a finger on .said carrie/nin opposition to said scale.

l. 1A speed indicator comprising a vertical screw having thereon discontinuous threads, and a carrier free to slide therealong and provided with means engagingsaid threads, said discontinuous. threads decreasing in length upwardly.' f

5. A speed indicator comprising a vertical screw Vhavingthereon discontinuous threads, av'carrier free-to slide therealong and provided with `means engaging Isaid threads, and a scale along which said carrier slides, said discontinuous threads decreasing in length upwardly, a i

6. A speed indicator comprising a vertical screw having thereon discontinuous threads, .a carrier free to slide therealong and provided with means engaging said threads, a scale along which said carrier slides, anda Vfinger on said carrier in apposition to said scale, said discontinuous threads decreasing in length upwardly.

7. Ai speed indicatorcomprising a vertical screw, a carrier slidablymounted and free lto travel in a path parallel with the vertical screw, the vertical screw having fixed ccntinuous threads and means comprisingl a screw engaging member` projecting outwardly from the carrier into the path ot the threads` and held against movement in any, direction except parallel with the axis `of the screw for intermittently raising the carrier along Vthe screw' responsive to the rotation thereof.

S. A speed indicator comprising a screw threaded spindle, means ttor rotating it, said spindle having beveled fiat sides interrupting the screw-threaded portions, a carrier slidablel parallel with said spindle, and a spring mounted on said carrier in engagement wth said screw, said spring being always held in line with the screw threads.

9. In a speed indicator a dial, a pointer mounted for movement theiealong and means for operating thepointer comprising a screw-threaded cylinder ,having a plurality of slots in the peripheryinterrupting the screw-thread and ii'icreasing ,in width upwardly.

10. In a speed indicator a dial, a pointer mounted for vmovei'nent therealong land means for oiierating the pointer comprising a screw-thrczuled cylinder having a plurality of slots in the periphery interrupting the screw-thread and increasing` in width upwardly and a yielding connection between the cylinder and the pointer.

11. In a speed indicator a screw-threaded cylinder having a plurality of slots in the periphery thereof interrupting the screwthreadx and increasing in width upwardly 12. In a speed indicator a screw-threaded cylinder having a plurality of slots in the yperiphery thereof interrupting the screwthread and increasing in width upwardly and acarriage mounted for movement parallel with the axis of the cylinder and a yielding connection between them.

13. In a speed indicator a screw-threaded cylinder having al plurality of slots in the periphery thereof interrupting the screw-thread and increasing in width upwardly and a carriage mounted for/movement parallel with the axis of the cylinder and a Vconnection between them, said connection comprising a grooved roller in engagement with the screw-thread.

'14. Ina speed indicator a screw threaded cylinder having a plurality of slots in the periphery thereoiE interrupting the` screwthread and increasing in width upwardly and a carriage mounted for movement parallel with the axis of Athe cylinder and a .yielding connection between them comprising a grooved `roller and a spring upon whichit is mounted for rotation and which thrusts ,the roller yieldingly into engagement with the threads. l

15. In a speed indicator a screw-threaded cylinder having a plurality of slots in the periphery` thereof vinterrupting the screwrthread and increasing in width upwardly ,and aearriage lmounted for movement parallel with the axis. of the cylinder and a connection between them, said connection comprisinga grooved roller in engagement with the screw-thread, the grooves on said roller being substantially the sameshape and size as the screw-threads.

16. In a speed indicator a screw-threaded cylinder having a plurality of slots in `the periphery thereof interrupting the screw-threadr and increasing in width upwardly and a carriage mounted for movement parallel with theaxis of the cylinder and a yielding connection between. them comprising a grooved roller and a spring upon whichit is mounted for rotation and which thrusts the roller yieldingly into engagement with the threads, the, grooves on said roller being substantially the same shape and size as the screw-threads.

17. ,In a speed indicator a screw-threaded :cylinder having a plurality oli' slots .in the periphery thereof interrupting the screwthread and increasing in width upwardly and a carriage mounted tor movement parallel with the axis of the cylinder and a connection between them, said connection coinprising a grooved roller in engagement with the screw-thread, the axis of the roller being inclined to the axis of the cylinder.

18. In a speed indicator a screw-threaded cylinder having a plurality ofslots in the periphery `thereof interrupting the screwthread and increasing in width upwardly and a carriage mounted for Amovement parallel with the axis of the cyl'inderand a yielding connection between them comprising a grooved roller and a spring upon which it is mountedfor rotation andywhicli yleldingly into engage' thrusts the roller ment with the threads, the axis of the roller being inclined to the axis of thecylinder.

19. In a speed indicator a screw-threaded vcylinder'having a plurality of slots in the.A

the roller where they contact each other, liev in the same plane. v

20. In a speed indicator a screw-threaded cylinderhaving a plurality of slots inthe periphery thereof interruptingy the screwthread and increasing in width upwardly and a carriage mounted for kmovement parallel" with the axis of the cylinder and' av yielding connection between them comprising a grooved roller and a spring upon which it is mounted for rotation and which thrusts the roller yieldingly into engagement with the threads, the relative position of spindle and roller being such that the threads on the spindle and the grooves on the roller where they contact each other, lie in the same plane.

2l. In a speed indicator a screw-threaded cylinder having a plurality of slots'in the periphery thereof interrupting the screw-thread and increasing in width upwardly and a carriage mounted for movement parallel with the axis of the cylinder and a connection between them, the screw threads having an upper substantially flat surface and a lower sharply inclined surface.

22. In a speed indicator ascrew-threaded cylinder having a plurality of slots in the periphery thereof interrupting the screwthread and increasing in width upwardly and a carriage mounted for movement parallel with the axis of the cylinder and a connection between them, the screw-threads having an upper substantially flat surface and a lower sharply inclined surface, the

connection between the carriage and threads comprising a grooved roller, the grooves of which have upper sharply inclined surfaces and lower substantially flat surfaces to engage the thread.

23. In a speed indicator a screw-threaded cylinder having a plurality 'of-slots inthe periphery thereof interrupting-the screwthreadand 'increasing `in'width upwardly anda ca rriage mounted for movement parallel with-thel axis of the cylinder anda connection between them, saidlcafrriage beingv free tolmove'upwardly along the `cylinder at all times and under,v all circumstances, but

heldagainst movement "doi'vnwardly' along the `cylinder except when in line with one of said slots. i

24. A speed indicator comprising a screw threaded spindle, a carriage, a yielding connectionfbetween the carriage and the screw threads of spindle, the screw threads being discontinuous the length of the break in the threads increasingk upwardly, means for rotating the vspindle to bring the connection into intermittent operative connection with the screw threaded spindle to move the carriage along the screw, and yielding means for resisting such movement.

25. In a speed indicator comprising a e lscrew threaded cylinder, a slot in the periphery thereof interrupting the screw threads and increasing in width upwardly, meansv` forrotating the cylinder, a carriage free to move along the cylinder, and a member carried by the carriage adjacent the cylinder and so positioned as to be in register with the threads, butto be out of engagement with the cylinder when the slot is in register with the connection.

26. A speed indicator comprising a screw threaded spindle and means for rotating it, a carrier free to move along the spindle, slots in the surface of the spindle increasing in width upwardly, the screw threads on the periphery of the spindle being extremely narrow, there being a plurality of separate threads on the periphery of the spindle and a connection between the carriage and threads. e

27. A speed indicator comprising a screw threaded spindle and means for rotating it,

`a carrier free to move along the spindle, and

a connection between it and the threads, slots in the surface of the yspindle interrupting the threads and increasing in width upwardly, the screw threads on the 'periphery of the spindle being so arranged that each individual thread extending once around the spindle moves along the spindle a distance equal to the thickness measured accurately by the number of threads.

28. A speed indicator comprising a screw threaded spindle and means for rotating it, a carrier free to move along the spindle, anda connection between it and the threads, slots in the surface of the spindle interrupting the threads and increasing in width upwardly, the yscrew threads on the periphery of the spindle, being so arranged that each individual thread extending once around the spindle moves along the spindle a distance in the presence of two ywitnesses this 14th equal to the thickness measured accurately day of Lanuary 1915.

by the number of threads the vnumber of d y suchzthreads bengsuch thai', Jche sum of such GUY BLACIXBURN' `g threads and the number of slots s always JVtIyresses:

an uneven. number.

b 4 MINNIE M.'L1NDENAU, In testlmony whereof, I'afxmy slgnature CHRISTINA DEAN'S.

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Y o v Washington, D. C. 

